The objective of this research is to identify the structural features of mycolic acids and the mycobacterial cell wall lipopolysaccharide-mucopeptide complex that are necessary for antitumor activity in order, hopefully, to provide more active and less toxic immunotherapeutic agents for use in the treatment of cancer. Isolation procedures developed in this laboratory have provided, for the first time, mycolic acids as structurally pure molecular entities, which makes possible a thorough examination of their structures and the structural basis for their activity.